Aims: Investigating events and complications associated with long-term anticoagulant use in patients with prosthetic heart valve replacement and analysing factors contributing to such events and complications. Materials and Methods: This was a retrospective cross-sectional study in 250 clinical records of prosthetic heart valve in patients hospitalised in Vietnam National Heart Institute - Bach Mai hospital from 2009 to 2011 due to such events as INR values out of therapeutic range (INR2
INR3,5) or anticoagulant related complications including: haemorrhage, valve thrombosis and embolism. Results: The percentage of patients whose INR values fall out of therapeutic range account for 51.2 percent (of which the events of INR2 are more common than those of INR3.5, being 27.6 percent and 23.6 percent respectively)
bleeding and embolism complications make up 48.8 percent (of which haemorrhage constitutes 39.2 percent, mainly subcutaneous and mucocutaneous bleeding of 18.4 percent, gastrointestinal bleeding and cerebral bleeding being 11.2 percent and 2.4 percent respectively
thromboembolic complications ad:ount for 9.6 percent, with ischaemic stroke making up the most proportion of 4.4 percent while valve thrombosis complications being less common). Anticoagulant dosage is directly related to events and complications in patients hospitalised. A sintrom (acenocoumarol) dose 2mg per day is related to INR values being under therapeutic range and higher risk of thromboembolism. A sintrom (acenocoumarol) dose 2mg per day is associated with more bleeding and INR levels beyond therapeutic range given p value 0.05. It is more likely for patients who did INR test less than one time per month to avoid haemorrhage and thromboembolism complications than those who did INR test over one time per month given p value 0.05. Conclusion: The events and complications of patients with prosthetic heart valve replacement use lifelong Vitamin K antagonist related anticoagulant dosage and patients' INR test time.